In various branches of industry, valve-controlled filling systems are applied for filling liquid products into containers. The containers are, most often, bottles. Problematic, in such case, is, frequently, foam formation during the filling process. If the product being filled is a liquid soap, for example, hair shampoo, then foam formation, which is caused by air bubbles during the filling, can easily bring about an overflow of the shampoo bottle during the filling event. Overflow even at a single filling station can cause the shutdown of the entire filling system. Depending on how much product has overflowed, extensive cleaning measures may be necessary.
The amount of product filled in each filling event is frequently measured with flow measuring devices (e.g. Dosimass, Dosimag, of the firm, Endress+Hauser) and adjusted via a metering control-unit.
If air bubbles occur during a filling event, then the flow measurement is more or less disturbed, depending on the measuring principle. The flow values delivered by the measuring device deviate from the actually present flow. In the case of Coriolis, mass flow measuring devices and in the case of magneto-inductive, flow measuring devices, complex methods are known for air bubble detection. These complex evaluating methods, however, require a certain amount of time, before the device can figure out that air bubbles are present and then display such information e.g. on its status output. For fast filling events, with filling times under a second, such bubble detecting methods are not appropriate.